Electronic – Safe inverter circuit to power neon indicators

inverterneon

I bought some neon indicators from eBay. I want to find a safe way to power them so we can do some experiments on solderless breadboards.

I can obviously power them from mains (120VAC/60HZ USA), but that's not safe for handling on a solderless breadboard. 🙂

I built the following circuit from parts lying around. At 12VDC input I get 150V pulses at 140Hz, <1% duty cycle. Obviously this only causes one electrode in the neon tube to illuminate.

Two questions:

  1. How dangerous would this circuit be in comparison to 120VAC mains? I realize this unit's maximum current output would be orders of magnitude less than mains…

  2. Is there a simpler, better circuit that doesn't require hard-to-source components like inductors and opamps? Full-swing AC output would be preferred from a 9VDC battery: something kids could build without me worrying they would electrocute themselves.

I seem to recall Forrest T. Mims illustrated a simple high voltage output circuit with just a couple components, but I can't find it.

Easily sourceable components for this project include resistors, capacitors and general purpose transistors, as well as diodes, LEDs… We also have a few wall-wart transformers we could tear apart if needed.

schematic

simulate this circuit – Schematic created using CircuitLab

Best Answer

Two answers:-

  1. The output is floating so it's safer than the mains. It's like your shaver socket.
  2. You could buy something like a ready made HV psu It probably has less chance of exploding than a home brew device. It has both AC and DC outputs.

But another point I'd make is that solderless breadboards are small things for plugging LEDs into. The gaps between contacts are fairly small, and they won't be rated for 150V+. Plain vero board might be a better alternative.

I kinda asked something similar when I wanted to mess with some HV stuff here. There are some useful dimensions there in the answers.

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